Give this character a power action and roll a d6; a single adjacent opposing character is knocked back from this character a number of squares equal to the result. When this character hits with an attack, you may choose that it generates knock back if it doesn’t already.

2012 Wording: Give this character a power action and roll a d6; a single adjacent opposing character is knocked back from this character a number of squares equal to the result.

Official FAQ

•(Players Guide, 2014): Though not an attack, this power targets the figure(s) being knocked back.

•(HeroClix Website 04-30-2013): Like Mind Control and Plasticity, Force Blast has received a pretty significant upgrade. On the one hand, it still work exactly like it did before, allow your character to knock back an adjacent character without needing any kind of attack roll: just assign a power action and roll the d6 for instant knock back. But now there is brand new addition to its normal effects. Now, anytime your character successfully attacks a character, you can choose to knock back that character back without needing to roll doubles! Note that this “extra” knock back only occurs if the character wouldn’t otherwise be knocked back… you won’t get to knock back a character twice if you happen to roll doubles. Also, since it says “may”, this new part is entirely optional. If you’d rather not knock back the target (maybe you want it to stick around for a follow up attack), then you don’t need to use this new part of Force Blast. Lastly, bear in mind that this knock back is not any different than rolling doubles. So if the attacked character has Charge or another game effect that causes it to ignore knock back, it isn’t going anywhere.